anthropic[minor]: Add tool_choice arg

docs/core_docs/docs/integrations/chat/anthropic.mdx

@@ -79,6 +79,42 @@ import AnthropicSingleTool from "@examples/models/chat/integration_anthropic_sin
 See the LangSmith trace [here](https://smith.langchain.com/public/90c03ed0-154b-4a50-afbf-83dcbf302647/r)
 :::
 
+### Forced tool calling
+
+import AnthropicForcedTool from "@examples/models/chat/integration_anthropic_forced_tool.ts";
+
+In this example we'll provide the model with two tools:
+
+- `calculator`
+- `get_weather`
+
+Then, when we call `bindTools`, we'll force the model to use the `get_weather` tool by passing the `tool_choice` arg like this:
+
+```typescript
+.bindTools({
+  tools,
+  tool_choice: {
+    type: "tool",
+    name: "get_weather",
+  }
+});
+```
+
+Finally, we'll invoke the model, but instead of asking about the weather, we'll ask it to do some math.
+Since we explicitly forced the model to use the `get_weather` tool, it will ignore the input and return the weather information (in this case it returned `<UNKNOWN>`, which is expected.)
+
+<CodeBlock language="typescript">{AnthropicForcedTool}</CodeBlock>
+
+The `bind_tools` argument has three possible values:
+
+- `{ type: "tool", name: "tool_name" }` - Forces the model to use the specified tool.
+- `"any"` - Allows the model to choose the tool, but still forcing it to choose at least one.
+- `"auto"` - The default value. Allows the model to select any tool, or none.
+
+:::tip
+See the LangSmith trace [here](https://smith.langchain.com/public/c5cc8fe7-5e76-4607-8c43-1e0b30e4f5ca/r)
+:::
+
 ### `withStructuredOutput`
 
 import AnthropicWSA from "@examples/models/chat/integration_anthropic_wsa.ts";

examples/src/models/chat/integration_anthropic_forced_tool.ts

@@ -0,0 +1,84 @@
+import { ChatAnthropic } from "@langchain/anthropic";
+import { ChatPromptTemplate } from "@langchain/core/prompts";
+import { z } from "zod";
+import { zodToJsonSchema } from "zod-to-json-schema";
+
+const calculatorSchema = z.object({
+  operation: z
+    .enum(["add", "subtract", "multiply", "divide"])
+    .describe("The type of operation to execute."),
+  number1: z.number().describe("The first number to operate on."),
+  number2: z.number().describe("The second number to operate on."),
+});
+
+const weatherSchema = z.object({
+  city: z.string().describe("The city to get the weather from"),
+  state: z.string().optional().describe("The state to get the weather from"),
+});
+
+const tools = [
+  {
+    name: "calculator",
+    description: "A simple calculator tool",
+    input_schema: zodToJsonSchema(calculatorSchema),
+  },
+  {
+    name: "get_weather",
+    description:
+      "Get the weather of a specific location and return the temperature in Celsius.",
+    input_schema: zodToJsonSchema(weatherSchema),
+  },
+];
+
+const model = new ChatAnthropic({
+  apiKey: process.env.ANTHROPIC_API_KEY,
+  model: "claude-3-haiku-20240307",
+}).bind({
+  tools,
+  tool_choice: {
+    type: "tool",
+    name: "get_weather",
+  },
+});
+
+const prompt = ChatPromptTemplate.fromMessages([
+  [
+    "system",
+    "You are a helpful assistant who always needs to use a calculator.",
+  ],
+  ["human", "{input}"],
+]);
+
+// Chain your prompt and model together
+const chain = prompt.pipe(model);
+
+const response = await chain.invoke({
+  input: "What is the sum of 2725 and 273639",
+});
+console.log(JSON.stringify(response, null, 2));
+/*
+{
+  "kwargs": {
+    "tool_calls": [
+      {
+        "name": "get_weather",
+        "args": {
+          "city": "<UNKNOWN>",
+          "state": "<UNKNOWN>"
+        },
+        "id": "toolu_01MGRNudJvSDrrCZcPa2WrBX"
+      }
+    ],
+    "response_metadata": {
+      "id": "msg_01RW3R4ctq7q5g4GJuGMmRPR",
+      "model": "claude-3-haiku-20240307",
+      "stop_sequence": null,
+      "usage": {
+        "input_tokens": 672,
+        "output_tokens": 52
+      },
+      "stop_reason": "tool_use"
+    }
+  }
+}
+*/

libs/langchain-anthropic/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@langchain/anthropic",
-  "version": "0.1.18",
+  "version": "0.1.19",
   "description": "Anthropic integrations for LangChain.js",
   "type": "module",
   "engines": {
@@ -39,7 +39,7 @@
   "author": "LangChain",
   "license": "MIT",
   "dependencies": {
-    "@anthropic-ai/sdk": "^0.20.1",
+    "@anthropic-ai/sdk": "^0.21.0",
     "@langchain/core": "<0.3.0 || >0.1.0",
     "fast-xml-parser": "^4.3.5",
     "zod": "^3.22.4",

libs/langchain-anthropic/src/chat_models.ts

@@ -60,9 +60,20 @@ type AnthropicStreamingMessageCreateParams =
   Anthropic.MessageCreateParamsStreaming;
 type AnthropicMessageStreamEvent = Anthropic.MessageStreamEvent;
 type AnthropicRequestOptions = Anthropic.RequestOptions;
-
+type AnthropicToolChoice =
+  | {
+      type: "tool";
+      name: string;
+    }
+  | "any"
+  | "auto";
 interface ChatAnthropicCallOptions extends BaseLanguageModelCallOptions {
   tools?: (StructuredToolInterface | AnthropicTool)[];
+  /**
+   * Whether or not to specify what tool the model should use
+   * @default "auto"
+   */
+  tool_choice?: AnthropicToolChoice;
 }
 
 type AnthropicMessageResponse = Anthropic.ContentBlock | AnthropicToolResponse;
@@ -546,6 +557,26 @@ export class ChatAnthropicMessages<
     "messages"
   > &
     Kwargs {
+    let tool_choice:
+      | {
+          type: string;
+          name?: string;
+        }
+      | undefined;
+    if (options?.tool_choice) {
+      if (options?.tool_choice === "any") {
+        tool_choice = {
+          type: "any",
+        };
+      } else if (options?.tool_choice === "auto") {
+        tool_choice = {
+          type: "auto",
+        };
+      } else {
+        tool_choice = options?.tool_choice;
+      }
+    }
+
     return {
       model: this.model,
       temperature: this.temperature,
@@ -555,6 +586,7 @@ export class ChatAnthropicMessages<
       stream: this.streaming,
       max_tokens: this.maxTokens,
       tools: this.formatStructuredToolToAnthropic(options?.tools),
+      tool_choice,
       ...this.invocationKwargs,
     };
   }
@@ -910,6 +942,7 @@ export class ChatAnthropicMessages<
     }
     const llm = this.bind({
       tools,
+      tool_choice: "any",
     } as Partial<CallOptions>);
 
     if (!includeRaw) {

libs/langchain-anthropic/src/tests/chat_models-tools.int.test.ts

@@ -271,3 +271,72 @@ test("withStructuredOutput JSON Schema only", async () => {
   );
   expect(typeof result.location).toBe("string");
 });
+
+test("Can pass tool_choice", async () => {
+  const tool1 = {
+    name: "get_weather",
+    description:
+      "Get the weather of a specific location and return the temperature in Celsius.",
+    input_schema: {
+      type: "object",
+      properties: {
+        location: {
+          type: "string",
+          description: "The name of city to get the weather for.",
+        },
+      },
+      required: ["location"],
+    },
+  };
+  const tool2 = {
+    name: "calculator",
+    description: "Calculate any math expression and return the result.",
+    input_schema: {
+      type: "object",
+      properties: {
+        expression: {
+          type: "string",
+          description: "The math expression to calculate.",
+        },
+      },
+      required: ["expression"],
+    },
+  };
+  const tools = [tool1, tool2];
+
+  const modelWithTools = model.bindTools(tools, {
+    tool_choice: {
+      type: "tool",
+      name: "get_weather",
+    },
+  });
+
+  const result = await modelWithTools.invoke(
+    "What is the sum of 272818 and 281818?"
+  );
+  console.log(
+    {
+      tool_calls: JSON.stringify(result.content, null, 2),
+    },
+    "Can bind & invoke StructuredTools"
+  );
+  expect(Array.isArray(result.content)).toBeTruthy();
+  if (!Array.isArray(result.content)) {
+    throw new Error("Content is not an array");
+  }
+  let toolCall: AnthropicToolResponse | undefined;
+  result.content.forEach((item) => {
+    if (item.type === "tool_use") {
+      toolCall = item as AnthropicToolResponse;
+    }
+  });
+  if (!toolCall) {
+    throw new Error("No tool call found");
+  }
+  expect(toolCall).toBeTruthy();
+  const { name, input } = toolCall;
+  expect(toolCall.input).toEqual(result.tool_calls?.[0].args);
+  expect(name).toBe("get_weather");
+  expect(input).toBeTruthy();
+  expect(input.location).toBeTruthy();
+});

yarn.lock

@@ -211,9 +211,9 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@anthropic-ai/sdk@npm:^0.20.1":
-  version: 0.20.1
-  resolution: "@anthropic-ai/sdk@npm:0.20.1"
+"@anthropic-ai/sdk@npm:^0.21.0":
+  version: 0.21.0
+  resolution: "@anthropic-ai/sdk@npm:0.21.0"
   dependencies:
     "@types/node": ^18.11.18
     "@types/node-fetch": ^2.6.4
@@ -223,7 +223,7 @@ __metadata:
     formdata-node: ^4.3.2
     node-fetch: ^2.6.7
     web-streams-polyfill: ^3.2.1
-  checksum: a880088ffeb993ea835f3ec250d53bf6ba23e97c3dfc54c915843aa8cb4778849fb7b85de0a359155c36595a5a5cc1db64139d407d2e36a2423284ebfe763cce
+  checksum: fbed720938487495f1d28822fa6eb3871cf7e7be325c299b69efa78e72e1e0b66d9f564003ae5d7a1e96c7555cc69c817be4b901d1847ae002f782546a4c987d
   languageName: node
   linkType: hard
 
@@ -8865,7 +8865,7 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "@langchain/anthropic@workspace:libs/langchain-anthropic"
   dependencies:
-    "@anthropic-ai/sdk": ^0.20.1
+    "@anthropic-ai/sdk": ^0.21.0
     "@jest/globals": ^29.5.0
     "@langchain/community": "workspace:*"
     "@langchain/core": <0.3.0 || >0.1.0